Process for the preparation of deoiled sludge in combination with acid recovery



Patented Mar. 2, 1943 PROCESS FOR THE PREPARATION OF DE- OILED SLUDGE INCOIWBINATION WITH ACID RECOVERY Robert P. Ferguson, Cranford, and InsleyP. Jones, Basking Ridge, N. J., assignors to Stand ard Oil DevelopmentCompany, a corporation of Delaware No Drawing. Application July 10,1940, Serial No. 344,774

6 Claims.

This invention relates to improvements in the art of refining petroleumoils and relates particularly to the separation of a deoiled tar,sulfuric acid and oil from an acid sludge formed an acid sludge obtainedon treating the viscous lubricating oil stocks.

Another object of our invention is to recover from the acid sludge layerboth the entrained oil by treating a petroleum oil with sulfuric acid. 5and an oil freethermo plastic tar Which iS su An acid sludge is formedwhen a. petroleum able for use in the preparation of plasticizers andoil is reacted with sulfuric acid of high concenrubber-like plastics.tration. The acid sludge thereb formed is gen- According to thisinvention a viscous lubricaterally all-owed to separate and settle belowthe ing o S r example a vy Colombian d streated oil layer and thereafterremoved. Thi 10 tillate of 77 seconds Saybolt viscosity at 210 F., acidsludge may then be processed for recovery is treated with 54 lbs. of 98%sulfuric acid per of the unreacted acid by diluting with water and 100gallons of o e temperature maintained allowing the mixture to separateinto two or more during the treating p is about T e phases (tar, weakacid and il nd t i mixture of oil and sulfuric acid is agitated by'ditions). The amount of dissolved carbonaceous 15 blowing w air or y thes of a m ani a material in th id phase usually decreases th stirrer forsufficient time to complete the reacdecreased acidity and in rd r t bt ihigh @011. tion between the acid and oil. It is not theincentratingyields, it s de irabl t hav thi com tention to limit this invention tothe particular tent of carbonaceous material as low as possible. crudeOil distillate 1 0 e Particular amounts However, when the acidity ofthis phase is lower 20' 0f Sulfuric acid that S en o i ustration than25%, difiioulties are frequently encountered After the mixture has beenagitated for 1-0 to 35 in that stable emulsions are formed resulting inminutes, preferably 25 to 35 minutes, Water little or no acid recovery.In addition, the conequivalent to 5 0 f t e Vo ume o t e Sl centratingcosts increase with decreasing acidity formed is added at a un m a O aperiOd of this phase. Consequently the normal prac- 25 0f 5 to minutesthen the agitation is continued ti i sludge separation consists inemploying for at least 5 minutes preferably 5 to minutes sufficient watr to produce an acid phase 1: longer. The mixture is then settled toseparate -40% sulfuric acid content. This procedure the Sludge andtreated Oil a d t S e With-' gives high acid recoveries,.dissolvedcarbon condrFJLWII- Additional W equivalent to 9 o tents that are notexcessive and moderate con 0f Volume 0f the Sludge y t en be incentrating costs. This procedure is limited, h corporated in the sludgeand the mixture settled ever, in that it can only be applied effectivelyto at a temperature of It y esludges from naphthas and light lubricatingoil times be desirable to maintain t e mixture untreatments as little orno acid is recovered from (161 a pressure of about 25 lbs. in order toreduce viscous sludges from heavy lubricating oils. the evaporationlosses of water.

Consequently the practice has been to dispose A three er sepa a n s e yo ta d; of these heavy sludges by fiuxing with a light oil one an Oillayer Containing a a l amount of and burning or burning directly inspecial bunk suspended sulfuric acid (treated oil entrained in ingequipment.- This method of disposing of the sludge), one an intermediatetar layer which these sludges is an expensive operation, andreissuitable for use in the Drepamtiim 0f p isults in' boiler corrosion andatmospheric pollu- CiZerS d rubber-like p cs, and the bottom ti r Slayer of the diluted sulfuric acid. The separated It is an object of ourinvention to provide a tar may be treated with solvents to remove anymethod whereby sulfuric acid of high acid and J trace of oil lefttherein. The solvents that may low carbon content maybe readilyrecovered from 4'5 be used are liquefied hydrocarbons that are normallygaseous at room temperatures, methyl a1- cohol, etc. The separated acidusually contains from 58 to 66% of sulfuric acid and about 1% of carbonwhich carbon content may be further reduced on concentrating the acid tohigher acidity or may be substantially removed by treating with nitricacid.

This separated acid may be concentrated to 88% acidity by conventionalmethods such as hot which the final separation was carried out at 250 F.with a pressure of lbs. per square inch to prevent loss of water byevaporat on with lower yields of the sulfuric acid that was separatedout. The separation of the acid is shown to be dependent on thequantities of water added i. e. when sufficient water is added to obtaina dilute acid of 58% to 66% concentration, at least 60% of an acid witha carbon content not air blowing or vacuum concentration. The yield 1substantially over 1% is recovered. The total from th1s operat1on is ofthe order of 92% or quantity of water added usually amounts to 15%higher while the carbon content of the concento of the sludge volume.

TABLE 1 SEPARATION or HEAVY LUBE SLUDGES Efiect of water collectingoperation on acid recovery yields Modified Normal Modified Modified Lubetreating operation:

Distillate .vlscosrty Blow on water do Sludge separation:

Water addition.-. Settling temperature Acid recovery at 100 F- volumepercent" 1'.11111111135;streetcar 1) I:

(1) Based on acid available in sludge.

trated acid is about 0.8%. The resulting acid is suitable for use intreating other petroleum products as such or after being fortified to 92to 96% sulfuric acid concentration. J

The process was described with reference to batch treating oflubricating oils and batch regeneration but it is obvious that thisprocess may be run continuously. The essential features of the inventionare that the initial addition of water must be made with vigorousagitation in order to intimately incorporate the water in the sludge andthe acid concentration of .the result ing separated sludge must be 58 to66% to obtain the maximum recover of the acid and tar.

The results obtained by the thorough mixing of first quantity of waterwith the mixture of acid and oil that is being treated, followed by afurther addition of the water, when needed is illustrated in thefollowing Table 1. The process usually employed is the one where therequired amount of water is added in periods of 4-5 minutes to thesludge-oil mixture while undergoing vigorous agitation and then onlyagitated another 3 to 6 minutes and no acid is recovered. However, inthose cases where the agitation following water addition was continuedfor 16 to 18 minutes, according to this invention, good acid recoverieswere obtained. Furthermore, where water was added slowly for 16 minuteswith vigorous agitation without any further agitation such as blowingwith air, no separation of the acid was obtained:

- When finally settling at temperatures in the neighborhood of 220 F.the effects of the addition of various quantities of water to the sludgeis illustrated in the following Table 2. This sludge was initially mixedwith 10% by volume of water during the acid treating operation and thenmixed with 0 to 80% of additional water for the final separation of theacid, tar and oil. Results are also given of similar operationsin TABLE2 SEPARATION or HEAVY LUBE SLUDGES Effect of acidity of acid phase andtemperature of settling on acid recovery LUBE TREATING OPERATIONColombian distillate V/ 100 F 900 Acid treat lbs. 98% acid/100 gals 40Water collect vol. percent of sludge 10 Sludge settling Separated acidoperatlon Settling Water Re temp. F. addition H780 erg Volume Per centPer cent Per cent 200 0 68.0 20.0 220 10 65. 4 62. 1 220 20 58.0 61.6220 40 46. 3 2 49. 9 220 33. 8 2 28.6 3 250 0 68. 1 43. 4 250 10 64. 369. 7 250 20 55.2 64. 3 250 40 44. 7 42. l 250 80 31. 9 24. 6

1 Weight per cent, based on acid availabl th 1 Weak acid dispersedthroughout tar ph s e e S udge 3 +15?! pressure.

We claim: 1. In the refining of petroleum hydrocarbon oils by treatingthe petroleum hydrocarbon oil with sulfuric acid to prepare athermoplastic tar, the steps which comprise treating a viscous lubri-vcating oil with concentrated sulfuric acid at a temperature of about F.,agitating the mixture for 10 to 35 minutes while adding slowly at auniform rate, 5 to 10% of water based on the volume of sludge formed,allowing the mixture to settle, separating th sludge from the treatedoil, adding 10% to 20% of water to the separated sludge, maintaining themixture at a temperature of 225 to 250 F. and separating the sulfuricacid, the tar and the oil.

2. In the acid refining of hydrocarbon oils according to claim 1, themixture of concentrated sulfuric acid and oil is mixed for 25 to 35minutes.

3. In the refining of petroleum hydrocarbon oils by treating thepetroleum hydrocarbon oil with sulfuric acid to prepare a thermoplastictar, the steps which comprise treating a viscous lubricating oil withconcentrated sulfuric acid at a temperature of about 100 F., agitatingthe mixuniform rate, 5 to of water based on the volume of sludge formed,continuing the agitation ture for 5 to minutes while adding slowly at aV uniform rate, 5 to 10% of water based on the volume of sludge formed,continuing the agitation for 5 to minutes, allowing the mixture tosettie, separating the sludge, adding 10% to 20% of water to theseparated sludge to dilute the acid to 58% to 66% concentration,maintaining the mixture at a temperature of 225 to 250 F., separatingthe sulfuric acid, the tar and the oil and concentrating the sulfuricacid to a strength of at least 89.1%.

4. In the refining of petroleum hydrocarbon oils by treating thepetroleum hydrocarbon oil with sulfuric acid to prepare a thermoplastictar, the steps which comprise treating a viscous lubricating oil withconcentrated sulfuric acid at a temperature of about 100 F., agitatingthe mixture for 5 to 15 minutes while adding slowly at a for at least 5minutes, allowing the mixture to settle, separating the sludge, adding10% to 20% of Water to the separated sludge to dilute the acid to 58% to66% concentration, maintaining the mixture at a temperature of 225 to250 F., separating the sulfuric acid, the tar and the oil and treatingthe tar with a solvent to remove the oil.

5. In the refining of petroleum hydrocarbon oils by treating thepetroleum hydrocarbon oil with sulfuric acid to prepare a thermoplastictar, the steps which comprise treating a viscous lubricating oil withconcentrated sulfuric acid at a temperature of about 100 F., agitatingthe mixture for 10 to minutes while adding slowly at a uniform rate, 5to 10% of water based on the volume of sludge formed, allowing themixture to settle, separating the sludge, adding 10% to 20% of water tothe separated sludge to dilute the acid to 58% to 66% concentration, andreduce the carbon content to about 1%, maintaining the mixture at atemperature of 225 to 250 F. and separating the sulfuric acid, the tarand the oil.

6. In the refining of petroleum hydrocarbon oils according to claim 5,the separated acid is concentrated and the carbon content reduced to avalue of under 0.8%.

ROBERT P. FERGUSON. INSLEY P. JONES.

